1. Field of Invention
This invention relates to protective needle sheaths. More particularly, this invention relates to a device that protects persons who give injections from accidental puncture wounds and contact with hypodermic and other needles used to inject and withdraw fluids into and out of human and animal tissue.
2. Prior Art
It has long been recognized that puncture by a contaminated hypodermic needle can pose a serious risk of infection. This risk has taken on fatal proportions since the emergence of the AIDS virus. While accidental puncture is still the primary hazard, exposure of the technician or other person to body fluids and possible contamination has become a cause of concern. Such exposure can occur when a person contacts the hypodermic needle shaft after injection. In response to this risk, various needle protection devices have been proposed These devices are generally of four types.
One type employs an end capping device with an open tunnel that provides a guide for the needle shaft. By means of collapsible pivotal members or a foam rubber or plastic sleeve which may have an internally integrated spring, the end cap is attached to a hub which connects to the needle assembly and syringe usually by a friction fit. When an injection is given the collapsible portion allows the needle to penetrate.
U.S. Pat. No. 4,790,828 discloses an assembly comprised of an elongated conical needle cover that protects the needle assembly prior to use and a capping device attached to a hub by a tethering mechanism. The preferred tethering mechanism consists of two arms with a flexible shoulder joint positioned at the midpoint of each arm. By applying force to the neutrally positioned tethering device the capping device is forced over the distal end of the needle and locked in place by means of an internally positioned flange.
U.S. Pat. No. 4,775,369 discloses a needle protection device comprised of a sheath with an internal spring with one end of the sheath attached to the hub portion of the needle attachment and the other end of the sheath containing a molded tubular guide end member which houses the sharpened end of the needle. The sheath contracts during the injection to allow penetration. As the needle is withdrawn, the sheath expands to its original position.
U.S. Pat. No. 4,735,618 shows a protective device for a hypodermic needle comprised of a cylindrical sleeve friction fitted over the hub of the needle assembly and connected by two pivotally movable arms to a needle guard that has a central channel for passage of the needle during the injection and a needle pocket where the distal tip of the needle is placed after use. When force is applied along the needle shaft towards the sharp end point, the pivotal arms collapse by means of joints located on the ends and in the middle of each arm.
A second type of needle protector employs opposing pivotal arms to enclose the needle before and after an injection is given. U.S. Pat. No. 4,820,277 describes a device which uses two pivotally hinged opposing arms which can be opened and closed by means of a mechanical activator, to enclose the needle assembly. In the open position the opposing arms fold back and attach to the syringe barrel.
U.S. Pat. No. 4,664,259 sets forth a device which uses two antipodal members hinged to a needle assembly that can be opened and closed around a needle before and after an injection. These members are connected by a lever which provides for uniform movement of the opposing members from the open and closed positions. With this device the opposing members are locked at an angle perpendicular to the needle shaft.
The third type of needle protector employs a single arm with a slot that, in the closed position, covers the needle shaft and the sharp needle point. The arm can be pivoted away from the needle assembly by a hinge means. After the injection, the arm can be repositioned to cover the contaminated needle. U.S. Pat. No. 3,658,061 depicts the device described above. Similarly, U.S. Pat. No. 4,872,552 shows a first tubular section that attaches to the base of a needle assembly. A second tubular section is attached to the first by a hinge. This second section can be rotated away from the needle point and shaft. After the injection is completed, the second section is pivoted back over the needle and, by pushing a sliding element at the end of the tube, the cover is secured over the needle.
U.S. Pat. No. 4,838,871 discloses a device in which a needle guard is rotatably mounted to the base of a needle assembly by means of trundle studs which correspond to trundle bases in the movable element. A locking ring keeps the needle shaft and point enclosed within the needle guard. When this ring is rotated, a longitudinal slit is exposed allowing the guard to be pivoted away from the needle assembly before the injection is given.
U.S. Pat. No. 4,664,259 discloses a needle housing which is hinged to the base of the needle assembly so that the needle housing can be moved from its initial closed position covering the needle to an open position of 90.degree. and back to a closed position in which the now contaminated needle is secured within the housing by a parked hook-like protrusion.
A fourth type of needle protector includes a protective cover which is much longer than the needle which is employed. Approximately half of the length of the needle is encased in a plastic sleeve. A plastic tube is fitted over this sleeve. In the open position, the tube is secured to the base of the needle assembly. After use the tube can be biased along the plastic sleeve over the remaining portion of the needle shaft and over the sharpened end of the needle. A flange on the inside of the tube locks into a detente on the plastic sleeve thus preventing the needle from being contacted after use.
Each of these prior art devices has important limitations. Most of these devices still present a risk of accidental puncture when force is extended along the needle shaft perpendicular to the skin surface. Many of these devices leave a significant portion of the needle shaft exposed to contact by the person administering the injection after it has been withdrawn and is consequently contaminated with body fluids. Many of the described needle protection devices limit the length of the needle shaft that is available for penetration into tissue. As a result medication may not be delivered to the proper site or the needle may not be able to penetrate far enough to withdraw sample fluids. Several of these devices provide for locking mechanisms which can be prematurely engaged rendering the needle assembly and perhaps the syringe and its contents useless. Finally, each of these devices hampers the person giving the injection because of the cumbersome nature of their design.
Therefore, it is an object of this invention to provide a protective needle sheath for use with hypodermic needle assemblies.
It is another object of this invention to provide a protective needle sheath that eliminates the risk of accidental puncture before and after an injection.
It is still a further object of this invention to provide a protective needle sheath that completely encases the contaminated needle shaft to prevent skin contamination by body fluids after the injection.
It is still a further object of this invention to provide a protective needle sheath that keeps the entire length of the needle shaft available for maximum penetration into tissue.
It is still a further object of this invention to provide a protective needle sheath that can be operated with one hand without requiring the technician to place his or her finger near the sharpened needle end.
It is still a further object of this invention to provide a protective needle sheath that will allow the person giving the injection enhanced control over the syringe and needle resulting in a more efficient and accurate injection.
These and other objects and features of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description, drawings and claims.